The invention relates to mobile communication systems and particularly to a method for controlling a mobile subscriber's local operation in a mobile communication system, in which a mobile station is arranged to roam within a cellular network and to connect to a local cell.
One of the objectives in mobile communication systems has recently been to develop mobile station services to be more and more equal to the conventional services of the fixed network so that they could replace fixed-line services both in offices and at home. In other words, a subscriber or a company is provided with a service area to which specific cells are selected (known e.g. as special cells) where a local subscriber-specific service profile, for example, is defined. That is to say, services and tariffs dependent on the location of the subscriber are produced for the subscriber. Such a cluster of cells is referred to as a Localized Service Area LSA or an LGS area. The subscriber can be an ordinary home user, for example, whose LSA is part of the radio access network covering his home and its immediate surroundings. Within this LSA special tariffs can be offered only to the home subscriber. The subscriber can also be a company employee to whom the localized service area LSA forms a company-wide network that utilizes the radio access solutions in the premises, for example. In the LSA, special tariffs can be offered only for company employees. The LSA typically comprises a cell or a cluster of cells. The cells in the cluster of cells can also be dispersed.
One prior art alternative of implementing subscriber-and subscriber-group-specific localized service areas is a method in which mobile-station-specific lists of special cells are drawn up of one or more network cells, and the operation of a mobile station is controlled on the basis of said list of special cells. Such controlling may comprise e.g. connection primarily to cells which provide some special service, e.g. call charges below the standard tariff.
Another prior art solution to implementing localized service areas in a radio network is a method in which a mobile station measures the signal levels of a serving cell and neighbouring cells. A cell selection parameter is calculated for the measured cells on the basis of the measured signal levels, and the cell which is the best according to the cell selection parameters is selected as the serving cell. In the method, calculation of a cell selection parameter of certain cells is processed so that the probability of a special cell becoming selected increases in proportion to a standard cell.
The above solutions are substantially based on a list of special cells, which is included in the system and utilized in controlling the local operation of a mobile station. Definition based on cell-specific information, however, increases the amount of information to be stored, makes definition of configuration slower and increases the amount of work when changes are made to the network. By using the list of special cells all special services of a special cell can be defined as available to a subscriber, but within a cell it is not possible to provide subscriber-specific tailored special services.